CA1145109A

CA1145109A - Preformed sheet-like structures

Info

Publication number: CA1145109A
Application number: CA000353526A
Authority: CA
Inventors: John Hurst
Original assignee: WR Grace Ltd
Current assignee: GCP Products UK Ltd
Priority date: 1979-06-06
Filing date: 1980-06-06
Publication date: 1983-04-26
Also published as: HK57783A; ES492154A0; IT1131285B; GB2052378B; FR2458389B1; NL8003301A; AU5906180A; SE450229B; KR830002970A; AR220057A1; BR8003479A; FR2458389A1; ATA300680A; ES8102247A1; DE3020945A1; GB2052378A; AU538137B2; NZ193945A; JPS5628850A; DK243380A

Abstract

TITLE OF THE INVENTION
PREFORMED SHEET-LIKE STRUCTURES

ABSTRACT OF THE DISCLOSURE
A sheet-like structure comprising two layers of respective bituminous compositions, each including a polymer, one layer being substantially non-adhesive and the other layer being a pressure-sensitive adhesive and, between the layers and in intimate contact with each layer, a coating of an oil resistant material.
A method of preparing the structure includes the steps of forming one of the layers, spraying onto that layer, when it is hot, an oil resistant material in liquid form, allowing the liquid to solidify so that the material forms a coating on that layer, and applying the other layer, when it is hot, to the exposed face of the coating.

Description

This invention relates to preformed sheet-like structures and to methods of making them. The structures of the invention are particularly, but not exclusively, useful for application to concrete surfaces.
In the past, concrete surfaces such as flat concrete roofs have usually been sealed by application of hot asphalt, a roofing felt with the aid of hot bitumen, or sheet-like membranes laid with the aid of hot bitumen or solvent-or emulsion-based adhesives. Such methods suffered 10 from the disadvantages that they require the employment of skilled men, local heating of the bitumen or the use of liquid applied materials so that the labour costs are high.
To avoid this difficulty there previously have been proposed sheet-like structures comprising two layers of 15 bituminous material attached to each other, one layer being substantially non-adhesive and the other layer being a pressure-sensitive adhesive, the compositions of each layer having at least one polymer distributed therein.
In practice, the two layers may differ from one 20 another in the proportions of the polymer in the bituminous compositions and/or by reason of the use of different .
~ polymers or bituminous substances in them.

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11~5~09 A drawback with the prior proposals is that there is a tendancy for the oils in the bituminous substances to migrate from one of the layers to the other, and it has been founcl that this tendency is increased if the polymers in the two layers are different and have different affinities with oils. There is, in fact a need to use such different polymers as the polymer in what will be the upper layer must be of a type which offers good weather resistance while that in the lower layer must be of a type which 10 retains its adhesive properties so that over a long period of time the structure will remain adhered to any surface to which it is applied. Eventually, an equilibrium stage is reached and it can happen that the layer which was initially non-adhesive becomes adhesive while the layer 15 which was initially adhesive becomes substantially non-adhesive. In extreme cases, and in particular where different polymers are employed in the two layers, it can come about that the two layers actually reverse their properties. This is, of course, unacceptable, because 20 such a preformed structure cannot be regarded as a success if the two layers reverse or alter their properties after it has been installed.
One way in which it might be expectad ~hat this difficulty could be overcome would be including a preformed 25 ~ilm or foil between the two layers of bituminous material.
When this has been tried, however, the drawback is ~ i .

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encountered that delamination of the product tends to occur, for instance due to different coefficients of expansion, rendering the product useless initially or after only a short period of use.
According to the present invention there is provided a waterproofing sheet for waterproofing concrete structures and the like, said waterproofing sheet being of the type comprised of a preformed, pressure-sensitive-adhesive sheet laminate of (a) a first layer of polymer-containing bituminous composition which is pressure-sensitive-adhesive and (b) a second layer of polymer-contain-ing bituminous composition which is subst~ntially non-adhesive, at least one of said bituminous compositions containing oil which subsequent to lamination has the tendency to migrate between the two bituminous compositions (a) and (b), the improvement which comprises providing an oil barrier layer between the layers (a) and (b) by applying to a surface of (a) or (b) prior to lamination a coating of oil-resistant polymer in liquid form whereby intimate contact is achieved between the layer (a), said oil barrier layer, and the layer (b) to effect a more improved non-delaminating bond between such layers.
It is preferable, thought not essential, to employ an oil resistant polymer which presents a tacky surface when it solidifies.
Rather than take the step of providing a preformed film or foil between the two layers, or to try to modify that step so as to be more success-ful, an oil resistant coating is used which is in more intimate contact with 1145~09 both layers than could ever be achieved by a preformed further member. The coating is preferably formed by application of the oil resistant material to one of the layers, when it is hot, in liquid form so that the coating closely follows the microscopic contours of the surface of the layer to which it is applied. The liquid rapidly solidifies and the second layer is applied hot to the thus formed coating and in turn closely conforms to the microscopic con-tours of the surface beneath. As a consequence, far greater affinity and mutual adhesion between the layers and the coating, in effect a non-detachability, is obtained than can be obtained using a preformed film insert between layers, and a satisfactory oil barrier is achieved.
By the term "pressure-sensitive-adhesive" we mean in this specifica-tion a material which, at ambient temperatures and without the application of heat or a solvent will adhere permanently under normal hand pressure to a con-crete surface. Clearly, therefore, the pressure-sensitive-adhesive is for application to a surface to be covered, the non-adhesive surface being suitable for exposure.
The bituminous compositions of which the two layers of the structure of the invention are constituted each include at least one bituminous con-stituent, that is to say one or more of bitumen, asphaltic bitumen, tars and pitches and their derivatives both natural and synthetic ,. . .

' 1145~()9 and at least one polymer. The polymers may for instance be natural or synthetic rubber, elastomeric or non-elastomeric, there being no requirement for the polymers in the two layers to be the same or for the polymers to be uniformly distributed within the layers. The compositions of the layers can differ from one another as to the proportions of bituminous constituents to polymer, in the bituminous constituents, in the polymers or by reason of a combination of two or three of these features. For the adhesive layer, 10 preferably, the bituminous composition is a bitumen-rubber composition, preferably formed of natural or synthetic rubber, virg;n or reclaimed, blended into bitumen to provide a smooth mix. The ratio by weight of bitumen to rubber is preferably from 70:30 or 80:20 of 95:5, especially about 15 90:10. Alternatively the bitumen can be a blend of-different bitumen~-containing also, if desired, heavy or light mineral oils and other plasticisers. Generally, suitable bitumen compositions have softening points (measured by the Ring and~Ball method) of 70 to 195C and 20 penetration values of1~300 at 25C (100 g. 5 sec.-Institute of Petroleum method) the softening point and penetration value may vary, within these ranges, from one side of the layer to the other-, or they may be the same throughout ,. : . .
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If desired a-layer of reinforcing material can be contained within either or both of the layers. The ~1~51~9 ll~n-adh~sive layer of the structure can if desired ~e provided with an outer coating of a light mineral aggregate or metallic powder to increase its weathering propertieS.
A protective coating which can be physically removed without damaging substantially the self-adhesive layer of the structure can usefully be applied thereto for storage -and transportation purposes, as the structure will normally be supplied in roll form. A wide variety of materials can be used to provide the protective coating.
10 Paper having a release coating therebn, e.g. siliconised paper or paper having a coating thereon of a suitable polymer, is satisfactory. Other materials include films of organic polymers, particularly vinyl chloride polymers.
As stated, the structure is conveniently available in the 15 form of rolls and in use can be unrolled, the protective coating being simultaneou~ly removed, and laid directly into place.
In referring to the "non-adhesi~e" layer, we mean that this layer is substantially non-adhesive at ambient 20 temperatures but it will obviously be adhesive when sufficiently heated and will be so in the manufacturing atep. It can comprise any suitable bituminous composition including a polymer such as are well known to those skilled in the art~ If de~ired, this non-adhesive layer can be 25 treated to protect it from damage and/or so that it offers an improved keying surface for other material, e.g. concrete ~. ~ . .

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ll~Sl~9 or asphalt, subsequently applied thereto,- Thus this face can be textured or gritted.
In width, the structures can vary for instance from

2.5 to 120 centimetres or more, depending~upon the use to which they are to be put and generally they are at least 5 centimetreS wide, for instance 15-90 or 100 centimetres - wide with the larger range of widths being preferred where a whole surface, for instance a roof, is to be rendered waterproof. The thickness can also vary depending upon the 10 intended use, but in the adhesive layer will generally be greater than 0.025 cms in order to ensure good adhe~ion over a long period of time even if the underlying surface should move and expand and contractwith age and seasons.
While the thickness can be,as much as 0..6 to 0.9 cms, a 15 maximum thickness of the adhesive layer of 0.4 cms may be preferable to ensure against slippage, especially if the structure bears loads.
Among oil resistant materials which can be used for the coatiny on and between the layers and be applied in 20 liquid form according to the method of the invention there may be mentioned polyvinyl acetate, polyvinyl alcohol, a carboxylated-styrene-butàdiene ,polymer, a ,styrene-butadiene polymer with high styrene content, an aarylonitrile-butadiene polymer, an acrylonitril'.e-styrene-butadiene polymer, polyurethane, 25 polyvinylchloride, acrylic resins, chlorinated rubber ~ ..
and polymethacrylates but other natural or synthetic oil ~esist,ant polymers or - , v' .

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~SlV9 other ~uitable materials which can be applied in liquid form can alternatively be employed.
In one way of performing the method of the invention, one of the layers of the composition is firstly prepared and, while it is hot, the liquid is sprayed thereon. The heat of the layer quickly solidifies the liquid and immediately thereafter the second layer, while itself hot is placed in contact with the thus formed coating on the first layer. The two layers are thus bound to one another, 10 and each coated most intimately by the coating which is compatible w~h both layers. An extremely good and even contact between the coating and the first layer is obtained by reason of the initial application in the form of a liquid, and this enhances the coating effect with regard to 15 the second layer. '~ith the coating in place, oil migration from one layer to the other can be avoided where it might take place for instance by reason of different oil contents, or by reason of different polymers in the two layers or both.
The structures are intended for use in providing a ZO waterproof seal over a surface, particularly a concrete surface, by applying the adhesive layer to the surface, a plurality of overlapping structures being used if necessary in order to form a continuous membrane over the whole surface.
The structure may be left exposed to the weather, or, if 25 desired, after the structure has thus been applied, another surface, e.g. another mass of concrete, a sand or cement :

11~5109 screed or other floor finish, a layer of asphalt or a cladding material, can be placed on the structure or can be formed in situ.
Exa~ples of suitable materials for the reinforcement for incorporation within the layers are glass fibre (woven, mesh, tissue or strand), synthetic polymers (woven, mesh or strand), expanded or perforated metal or fabric (woven or non-woven).
The structures can be used on floors and roofs, 10 particularly the flat roofs-of factories or blocks of flats. They can slo be used on bridge decks where the structures are applied as indicated above and hot asphalt is laid on top as a wearing course.
The accompanying drawing is a cut-away perspective 15 view of a structure according to the invention. The sheet-like structure shown comprises a pressure sensitive adhesive layer 10 of a bituminous-rubber composition. Upon the upper face of layer 10 is a very thin coating of an oil resistant material such as 20 polyvinyl acetate in intimate contact with layer 10.
In intimate contact with coating 11 is an upper layer o a bituminous composition 12, this being substantially non-adhesive. In use, the structure which is supplied in rolls, is laid in adjacent strips on a surface to be 25 protected, such as of concrete, with the lower surface of layer 10 in contact therewith, normally witXout any~

.... .... ,. ~ . -. , , ~, -- 1 o preparation save removal of dust from the concrete although in certain situations use of a primer may, despite the self adhesive nature of the layer 1~, be recommended. A release sheet, not shown, is provided on the lower surface of layer 10 to be removed prior to installation.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a waterproofing sheet for waterproofing concrete structures and the like, said waterproofing sheet being of the type comprised of a preformed, pressure-sensitive-adhesive sheet laminate of (a) a first layer of polymer-containing bituminous composition which is pressure-sensitive-adhesive and (b) a second layer of polymer-containing bituminous composition which is substantial-ly non-adhesive, at least one of said bituminous compositions containing oil which subsequent to lamination has the tendency to migrate between the two bituminous compositions (a) and (b), the improvement which comprises providing an oil barrier layer between the layers (a) and (b) by applying to a surface of (a) or (b) prior to lamination a coating of oil-resistant polymer in liquid form whereby intimate contact is achieved between the layer (a), said oil barrier layer, and the layer (b) to effect a more improved non-delaminating bond between such layers.

2. The improved waterproofing sheet of Claim 1 wherein said oil-resistant polymer is selected from the group consisting of polyvinyl acetate, polyvinyl alcohol, a carboxylated-styrene-butadiene polymer, a styrene-butadiene polymer with high styrene content, an acrylonitrile-butadiene polymer, an acrylonitrile-styrene-butadiene polymer, polyurethane, polyvinylchloride, acrylic resins, chlorinated rubber and polymethacrylates.

3. The improved waterproofing sheet of Claim 1 wherein the polymer in at least one of said bituminous layers (a) or (b) is a rubber.

4. The improved waterproofing sheet of Claim 1, 2 or 3 wherein the sheet is at least 15 centimeters wide.

5. The improved waterproofing sheet of Claim 1, 2 or 3 wherein the surface of the adhesive layer (a) remote from layer (b) has a removable pro-tective sheet thereon.

6. The improved waterproofing sheet according to Claim 1, 2 or 3 wherein said oil resistant liquid polymer is applied to the layer (a) or (b) when such layer is hot.

7. The improved waterproofing sheet according to Claim 1, 2 or 3 wherein both layers (a) and (b) are hot when brought into contact with said oil resistant polymer.